i5 vs i7
Intel recently released processors featuring it’s new Sandy Bridge architecture, and those in the market for a new computer may want to be updated about the changes this has had on Intel’s popular i5 and i7 CPUs. Both are excellent processors, but there are a few significant differences between i5 vs i7.
One could easily guess from the names that these CPUs are of the same family, but on inspection they are designed quite differently. I’ll spare the reader any more commentary than this; the specs readily speak for themselves.
This article focuses on the desktop variants of the Inside family of processors.
One significant advantage that the i7 has over the i5 is cache size. Cache is a place for the CPU to store data that it finds itself using frequently. In essence, it operates very similarly to to RAM, except that it’s local to the CPU.
The diminished necessity for interaction with RAM can be a significant benefit to processor speed on the whole. The i7 outdoes the i5 by a significant margin on this spec: the i7 has an 8MB cache, while the i5 has only 6MB.
The i5 and the i7 are both quad core processors, but hyperthreading is featured only in the i7, giving it another great advantage. You may have heard of multi-core processing before. It does not increase processing speed per se, as you may have been lead to believe; instead, it refers to the number of processes that can be handled simultaneously by the CPU by introducing additional cores.
Previously, CPUs could serve only one thread per core. Hyperthreading increases that number to two, allowing for 8 simultaneous threads on a quad-core processor. When we look at the i5 vs i7, considering the i7′s hyperthreading coupled with both processors’ respective caches, the i7 will be considerably faster.
To see how the differences in these processors’ designs manifest themselves in real-world situations, here are some results from i5 vs i7 tests performed by Nate Ralph and his crew at PCWorld. These numbers are scores produced by WorldBench, a program which measures CPU performance by running a typical process live.
The i5 scored 150, 
and the i7 scored 156 on WorldBench overall. However, in one instance, a computer equipped with an i7 overclocked to 5GHZ scored 223. This was an unprecedented WorldBench score across all CPUs, according to PCWorld.
Tests were also run on games, which are some of most demanding pieces of software typically run by consumer computer users. These are the WorldBench scores for Dirt 2, Call of Duty 4, S.T.A.L.K.E.R.: Call of Pripyat, and Just Cause 2. All were run at 2560×1600 resolution at the highest possible settings.
*Dirt 2
i5: 132.97 — i7: 142.25
*Call of Duty 4
i5: 78.60 — i7: 78.90
*S.T.A.L.K.E.R.: Call of Pripyat
i5: 22.72 — i7: 22.75
*Just Cause 2
i5: 38.80 — i7: 38.96
In some of these cases, there isn’t a significant difference in performance between the i5 vs i7. Although the scores produced are similar, PCWorld admitted that an outdated graphics card used during testing affected the results, limiting the potential impact of the i7′s hyperthreading in overall performance.
Both processors scored very poorly without any graphics card present at all, so a discrete graphics card is still recommended for users who need their computer to deliver for gaming or high-end media production.
To conclude, the i7 predictably outperforms the i5 due to it’s greater cache in combination with it’s hyperthreading capability. However, when put to the test, these processors both performed very well, and a confident judgment of their general value when considering their cost is difficult to provide.
Dedicated power users may spare no expense for the i7, given its potential for software optimized for multi-threading, but typical consumers may find themselves perfectly happy with an i5, especially given its significantly lower cost.
SOURCES: (http://www.pcworld.com/article/215318-2/lab_tested_intels_sandy_bridge_cpus_deliver_blazing_speed_and_energy_savings.html)